A larger retail space, archives room, gymnasium and hall are all part of the second stage of changes the organisation has planned.
Major Glenn Anderson said the plans started coming together about eight years ago with stage one - redevelopment of the Bridge programme and Employment Plus areas - completed in 2008.
The next stage, which started in May, included relocating the central city Family Store to a building on the corner of Jervois and Princes Sts.
"Big, bold" signs would "upgrade the communication" to the public, he said.
"For the last 10 years we've been trying to up our Family Store image - moving from dark, poorly lit, smelly op shops to more professional retail stores.
"We should be able to serve the wider public more efficiently by ensuring we provide a wider range of products ... and providing a much more pleasant experience for people. I think that will have an impact on our donations as well," Maj Anderson said.
The existing shop will be used temporarily for processing, before a city-wide warehouse is completed to handle "all pick-ups and all donations" along with deliveries of goods for the city's three stores.
Independent management would ensure no favouritism occurred in supplying individual stores from the warehouse, and pricing structures were being improved, Maj Anderson said.
"There have been some discrepancies between our stores and we are trying to get a pricing structure which is consistent," Maj Anderson said.
The current store will be reconfigured to include a commercial kitchen, gym, lounge, library, archive room ("to tell the story of the Salvation Army"), a new chapel and hall.
Demolition of two warehouses on site would provide space for a further 32 car parks.
"I think it gives us good opportunities for the future ... opportunities for people to connect."
He expected the entire project, which was largely funded by the sale of buildings in King Edward St in 2009, to be finished in the middle of next year.
The retail store would open in about three weeks.
